Wednesday, 6 February 2013

8. Internship. Oro-nasal fistula in an Old Chihuahua

This
text describes the processes of how a vet diagnoses & treats a case of oral
tumours with tooth root abscess and oronasal fistula in an older Chihuahua.
These processes form part of the Standard Operating Procedures at Toa Payoh
Vets.

Owner
noticed that the dog had swelling on the right side of the cheek for more than
two weeks and later brought the dog to Toa Payoh Vets.

The
patient: Chihuahua, Male, 10 years old, Singapore

There was swelling on the right side of the cheek
however the appetite was still normal. The swelling had been there for more
than two weeks. It seems like the old dog had oronasal fistula and tooth root
abscess.

Life has not ended for this old dog as it was given
a second chance by its owner. He had once been abandoned and later he found
home with this kind hearted Singaporean who flew him all the way from
Australia. He had journey far to reach his home sweet home.

The dog’s mouth is seldom examined by most dog
owners and bad breath is usually tolerated by many Singaporean dog owners. They
also seldom pay attention to the mouth part of their pet as long as the dog is
eating without a problem.

Dental check up is not usually done and tartar will
usually build up and rotten teeth fall off. Many owners are not bothered or are
ignorant that dogs also need to have regular dental check up and dental care.
However, the younger generation of Singaporeans are better educated and more
concerned about the welfare of the old pets.

Back to my case.

One fine day on
late January 2013, the owner of a male, 10-year-old Chihuahua noticed a
swelling on the right cheek and brought it to Toa Payoh Vets.

At Toa Payoh Vets, Dr Daniel Sing was on duty. I was present.
“This looks like a case of tooth root abscess as you can see that the teeth
are rotten and filled with tartar. There may also be oronal fistula. It is an
abnormal communication between the oral and nasal cavities involving the soft
palate, hard palate, premaxilla, or the lip” said Dr. Daniel.

Is it a case of
tooth root abscess and oronasal fistula?

“So what are the
treatment options available?” asked the owner.

“For this case,
we would recommend to go through surgery to remove all the affected teeth and
clean the abscess” explained Dr. Daniel.

“But then how
would my dog eat without teeth” the owner said.

“Don’t worry, the
dog can eat soft canned food or even boiled chicken breast and porridge”

The
financial
costs and risk must be explained fully before any operation is done.
But the owner must give his consent and that is where personality and
financial conflicts come in. He must also be aware of the risk involve
especially in older dogs.

Blood test

Health screening is strongly advised before
anaesthesia and surgery for all patients, esp. in the older dog.

Anaesthetic risks are much higher in old dogs.
There is always the possibility that the older dog may die on the operating
table. When the owner hears that the dog may die on the operating table, he
may decide not to get the surgery done. Some deem the vet incompetent and
consulted another vet. A health screening should be suggested by the vet to let
the owner knows whether the risks are high or not.

"I advise a blood test to screen the health of the Chihuahua," Dr
Daniel said. The owners must consent to take the anaesthetic risk if
they give permission for the surgery as in this case. No surgeon can
guarantee zero risk in any anaesthesia, whether in people or animal.

This blood test indicates that the liver and
kidneys were functioning normally.
"OK," the owner consented to the
surgery.

Antibiotics were given to the dog.

IV anaesthesia
without Intubation.

Anaesthesia. What
type? IV, gas or both? IV anaesthesia is shorter acting than gas anaesthesia.
Intubation (a breathing tube connects anaesthetic gas and oxygen to the dog)
is usually done in dental extraction.

After
the dog had been anaesthetised, I discover that there was a big tumour about
the size of palm size dough growing from the soft palate. This tumour occupied
the whole oral cavity and the plan now had changed. We had to remove the tumour
and the teeth as well. Therefore we can’t intubate the dog as the tumour is
obstructing the endotracheal tube.

“Call
the owner and inform him about the tumour and the plan to remove it and ask for
his consent”

The
owner gave his permission to proceed and the surgery continued.

Dormitor
IV at 25% of calculated dosage for young healthy dog was sufficient for
electro-sugical excision. Dental extraction was done after that.

The
old dog survived the anaesthesia and that was what mattered most for the owner.
It is not always possible for every old dog to survive anaesthesia during
surgery. Therefore it is wiser to remove the tumour when it is smaller and when
the dog is younger.

Histology

“Is
the soft palate tumour cancerous or not?” the owner asked.

“Nobody
can tell from the physical appearance,” I said. “The tumour needs to be
analysed by the laboratory and the tumour cells can be seen under the
microscope if there are any. This is the process of histology. Do you wish to
get the tumour sent for histology?”

It
is best to get the owner’s permission to send the tumour for histology to
determine its state, as some owners may have budget constrain or do not wish to
spend more money.

Electro-Surgery

It
is unprofessional to give medication to the owner to treat the oral tumour as
some owners may insist on having them as an alternative to the high risk of
anaesthesia during surgery as it will not disappear.

Electro-surgical excision of the soft palate
tumour including extraction of molar teeth.

“The tumour can be removed from its stalk by
using electro-cauterizer to avoid losing too much blood,” said Dr. Daniel. Then
after removing the tumour, the dog started to wake up from anaesthesia, so it
had to be gassed with Isoflurane. When it was down, Dr. Daniel proceeded with
dental extraction of the molar and drainage of the pus.

Histology
Lab Result

The result of the histology came out and the
nodule is covered by squamous epithelium with overlying parakeratosis. At the
centre, there were irregularly-shaped trabeculae of woven and lamellar bone.
There is no evidence of malignancy. So this is good news for the owner is it
was not cancerous.

Conclusion:

The final diagnosis from the histology is
ossifying fibroma mass, with tooth root abscess and oronasal fistula. The dog
was put on antibiotic and two days after surgery it was allowed home.

BE KIND TO
YOUR OLDER DOG. EXAMINE YOUR OLDER DOG'S MOUTH WEEKLY FOR ORAL TUMOURS.
SMALL TUMOURS ARE EASIER TO REMOVE AND THERE IS A MUCH LOWER ANAESTHETIC RISK.

Tips & Advices:

Post
surgical management.

1.Owner need to come back for review every 3 months for the
next 12 months. Owner needs to be advised and reminded by the vet but this is
seldom done by me.

2.The mouth of older dogs must be checked by the owner daily
and any mouth tumour can be removed when it is small. In this case, the whole
oral cavity had been filled with the tumour. It could have existed for some
months without the owner seeing it.

3.TIPS: old and unhealthy dogs (>5 years) must be given
25-50% of the calculated dosage of IV anaesthesia for younger dogs to lessen
risks of heart failure.